Rehabilitation Engineering:
Autonomous Toileting Assistive Device

ABSTRACT:

Our client is an eight year-old male with severe upper arm deformities and minimal grasping capabilities. The client currently requires an assistant to help him wipe after bowel movements. The client wants a discrete device that can easily be carried in a backpack and mimics a natural wiping technique. In order to help the client become more independent, we have designed and built an assistive device which aids in sanitation after bowel movement. Through an iterative technology approach to design, we have created a safe, portable, and pragmatic solution for our client’s needs. The device is placed on the lip of a toilet such that the client can wipe across a foam wedge with a wet wipe that he independently places atop the wedge. The final model will be integrated into the client’s life and increase his level of independence.

KEYWORDS:

assistive device, hygiene, toileting, wiping

BACKGROUND:

The purpose of this project is to design an effective wiping device which allows our client to be fully independent in his everyday life. Our client is an eight year-old male with severe upper arm deformities including fixed flexion contractures at both elbows of over 130 degrees. His right hand has one finger with no grasping capabilities while his left hand has two fingers with minimal grasping capabilities. The client currently requires an assistant to help him wipe after bowel movements.

In the United States alone, there are 1.9 million people living with limb loss. The birth prevalence of congenital limb deficiency has remained stable during the past 30 years at approximately 15.21 per 100,000 live births (1). Previous work has been conducted by Vanderbilt Engineering Science undergraduate students and by several private assistive technology companies. Little progress was made in forming a viable solution. Current solutions for similar patients include portable bidets and private assistants. Neither coincides with the capabilities and desired independence of our client.

Through an iterative technology approach to design, we have created a safe, portable, and pragmatic solution for our client’s needs. Our autonomous toileting device meets the client’s specifications, which include the need to be portable, compact, independently installable, easily loaded, sanitary and easily cleaned, and durable over time.

METHODS:

Figure 1: This photograph shows a side
view of Prototype A. (Click for larger view)

After an initial planning and brainstorming meeting, our group decided to approach this problem using an iterative design method. This process consisted of three distinct steps. The first step of our basic process was a brainstorming meeting in which we organized ideas and formed a tentative solution. Next, we constructed a rough prototype in order to visually demonstrate our thoughts. The prototype was then discussed and, in some cases, tested by our client. His feedback was held in the highest regard and was used to make changes and improvements on our next design. A total of three prototypes were constructed over the course of the project. A final design was modeled in SolidWorks and manufactured professionally using fused deposition modeling (FDM).

RESULTS:

Prototype A was constructed using household items including a simple scrubbing brush, a suction cup, and Velcro. The idea was that the client would stick the device to a stall wall before using the restroom. He would then stand up and rub against a wet wipe which was fastened around the brush part. The wipes could be easily torn off and disposed of after use.

Figure 2. (Click for larger view2)

After speaking to our advisor and client about this idea, we found several significant drawbacks. First, the potential failure rate of the device was high due to the nature of the suction cup. Although it adhered well to the wall, it was still susceptible to losing its grip if any significant downward forces were applied. Furthermore, the device had to be preloaded by someone other than the client. Finally, the placement of the device on a wall made it too awkward and embarrassing to use in a public place.

Prototype B was designed and constructed in response to these problems. It was made in a prosthetics lab where we heated up plastic (polyethylene) and molded it directly over a toilet. A hook was placed on the back side of this plastic to grip underneath the inside lip of a toilet and hold it in place. To create a wiping surface, we attached an arm and platform which protruded perpendicularly from the front of the toilet. A sculpted foam wedge was then affixed atop the platform. Four slits were created at the corners of the platform for the client to easily fasten a wet wipe over the top of the foam wedge. The wipe could be pulled off from a corner after use and disposed. Foam was used to cover the platform, thus preventing scratching and chafing.

This prototype was tested by the client and worked extremely well, although there were a few recommended improvements. The arm of the device flexed too much, which made it dangerous to put a lot of weight on it. Also, the finger slits were too stiff for the client’s underdeveloped fingers to penetrate. As far as sanitary measures were concerned, the separate components of the device left many small gaps where dirt and bacteria could easily build up. Finally, the clamp portion of the prototype was not designed with a universal toilet fit in mind.

Figure 3: This photograph shows a side view of Prototype C. (Click for larger view)

Taking these concerns into consideration, we began work on our final design. We set out to make the finished version more compact, stable, versatile, and sanitary. The first step was to redesign the plastic portions of the device so that we could create a computerized model and get it professionally manufactured. A custom piece was needed in order to reduce the number of crevices and give the product a smooth, sleek look. Before we modeled the device, we created Prototype C via similar methods as the previous prototype. This device was smaller, and the clamping portion was made to accommodate a broader variety of toilet bowls.

Prototype C was used to create a model in SolidWorks, which we then sent to a private company for manufacturing. The arm of the final device was made much thicker than our previous prototypes, thus preventing bending or breaking. When the finished plastic portion arrived, we made several additions. We used a soft rubber to create the finger slits. This made it easier for the client to attach wet wipes. The platform of the device was coated with foam, and the wedge was attached to the top of the platform, just as in Prototype B. Finally, we glued a layer of foam on the inside of the clamping portion of the device to fill the gaps between the plastic and the toilet. This provides us with some additional tolerance in adapting to varying toilet bowl sizes.

DISCUSSION:

Figure 4: This screenshot shows a 3D
model of our final design created in
SolidWorks. (Click for larger view)

The final prototype is a successful device that our client is able to install, load, use, and remove independently. It mimics the natural wiping technique used by most of the population and is compact enough to be discretely carried in public and at school, thus minimizing the social issues surrounding our client’s condition. The client and the client’s family are pleased with the solution we have developed. The sanitary concerns have been reduced as much as possible by the materials chosen for the device, as well by the type of wipe loaded and used with the device.

Despite our efforts to improve our design and better accommodate the client’s needs and desires throughout our iterative design process, there are several safety issues that cannot be eliminated due the nature of the device. Like any device that is used in toileting, the inability to maintain sterility is an ongoing challenge. We chose to make the device out of plastics that could be easily cleaned with bleach or other disinfectants daily, with the exception of the removable pieces, which can be thrown out and replaced.

As a portable device which is placed on the toilet but is not permanently attached, there are safety issues concerning movement of the device, as well as mechanical failure. As the client or user places force on the device, there is a possibility that this force and torque can dislodge the device or even cause it to break. We have taken these safety issues into consideration to the best of our ability. Due to the size and weight of our client, we do not anticipate that these risks will pose a significant problem.

While few individuals possess the exact deformities as our client, there are a significant number of individuals who possess a limited range of motion, weakness, or lack of independence. This assistive toileting device could serve as an option for someone with insufficient range of motion to wipe following a bowel movement. However, users must have enough strength, grasping ability, flexibility, and range of motion to ‘install’ the device before each use, as well as load the wipes. Individuals missing upper extremities entirely or without any digits would most likely be unable to use this device.

Future work on this design would include a better solution for fitting the device to different toilets. Also, further inspection of options for materials to construct different portions of the device might allow for a more sanitary design and practical use. Additional work on the design might include a version with an easy open-and-close hinge to make the device more compact. We chose not to use the hinge design due to our client’s limited strength and decreased grasping abilities. We would also like to identify other specific groups of users to which we can market our device.